Trade of heavy vehicle mechanic

4.6 Radiator

Where a radiator is mounted also depends on space - how the engine is mounted. A header tank can be mounted away from the radiator, where it provides a coolant supply, stored above the engine. It can be made of sheet metal, or hardened plastic.

The radiator has 2 tanks and a core.

The materials used in the radiator must be good heat conductors like brass or copper. Brass and copper are often used for tanks, combined with a copper core.

Modern vehicles often use plastic tanks combined with an aluminium core. This saves weight but still provides good heat transfer.

The core consists of a number of tubes that carry coolant between the 2 tanks. The tubes can be in a vertical downflow pattern, or a horizontal crossflow pattern.

A crossflow radiator fits more easily under a steeply sloped bonnet.

In the core, small, thin, cooling fins are in contact with the tubes. The shape of the fins increases the surface area exposed to the air.

Where coolant touches tube walls, and where the tubes touch the fins, heat is removed from the coolant by conduction, then by radiation and convection at the surface of the fins. Air rushing by carries the heat away.

Liquid emerges cooler at the bottom of the radiator. It travels through the lower radiator hose to the water pump inlet, then through the engine again.